1. Field of the Invention
The present invention relates generally to a battery tub tester for testing battery tub components during tub assembly and, more particularly, to a battery monitor and tester for testing batteries and battery tub components as they are being assembled in a battery tub for an electric vehicle, to determine whether each individual battery and component is acceptable prior to the battery tub being connected to the vehicle.
2. Discussion of the Related Art
Electric vehicles which run on electrical power stored in multiple batteries within a battery housing or tub are known in the art. The popularity of electric vehicles is on the rise as a result of many factors including consumer demand, emission concerns with internal combustion engines and increased government regulations. An assembled battery tub includes a certain number of batteries and battery components mounted and electrically connected in the battery tub in accordance with a particular assembly scheme. Once assembled, a lid is bolted to the tub and the tub is then bolted to the vehicle.
In one example, twenty-seven 12 volt batteries, three battery monitor modules (BMMs), and fifteen temperature sensors (thermistors) are mounted and electrically connected within the battery tub. The batteries are electrically connected in series, and a group of batteries is connected to each BMM such that an electrical connection is made between each adjacent battery and the particular BMM. A single temperature sensor is used to sense the temperature of two adjacent batteries. During vehicle operation, the BMMs monitor the battery voltage and battery temperature of the individual batteries within the tub, and provide a signal indicative of these values to a controller to be processed for visual indication to a vehicle operator. U.S. Pat. No. 5,646,534 issued to Kopera discloses a battery monitor module for an electric vehicle of the type being discussed herein.
A problem exists with the above-described technique of assembling a battery tub for an electric vehicle. That problem has to do with the lack of ability, in the known art, to test the batteries, BMMs, and thermistors, and the various connections, as they are being assembled in the tub. Occasionally, one or more of the batteries being mounted and connected in the tub may be defective, and not be able to produce its intended charge. Additionally, it is typically necessary that the batteries all have approximately the same voltage capacity (generally on the order of 12-131/2 volts) and voltage spread. Further, other tub components, such as the BMMs and the temperature sensors, may be defective and not operate properly. Also, the various connectors and leads may be defective or not connected properly, and not provide the desired electrical connections between the tub components.
Currently, no technique exists for determining whether the battery tub is being assembled properly, and whether the batteries and electrical components being inserted in the tub will operate as intended. Thus, the assembler of the tub would not know that the battery tub will not operate correctly until the battery tub was completely assembled, mounted to the vehicle, the vehicle was started, and the readouts from the BMMs were determined. After the battery tub was secured to the vehicle, and it was determined that there was some problem with the battery tub operation, it was necessary to remove the battery tub, and individually check each of the connections, batteries and other components to locate the problem. Because the battery tub is extremely heavy and is connected to the vehicle by several bolts, the manpower required to connect and remove the tub is intensive, as well as the manpower and lost time required to test the individual batteries and components once it has been removed.
What is needed is a system and method for sequentially testing the individual batteries, battery tub components and connections in a battery tub as the battery tub is being assembled, so as to insure that the battery tub will operate correctly prior to the tub being connected to the vehicle. It is therefore an object of the present invention to provide such a system and method.